This invention relates to a device for controlling the flow of a fluid, and more particularly concerns a valve device for precise regulation of the rate of flow of a fluid within a confining conduit.
Valves of various designs have been proposed for regulating the flow of a fluid within a confining conduit. Most such valves involve a controllably movable member adapted to mate with a stationary member or seat. When the mating is complete, total blockage or closure is achieved, thereby preventing any flow of fluid through the valve. When the movable member is close to but not in contact with the seat, flow of fluid is permitted, but the effective cross-sectional area of passage through the valve is reduced considerably from the fully open position where the movable member and seat are at their maximum separation. Since the rate of flow of a fluid is dependent upon the cross-sectional area of a passageway at a given pressure drop across the passageway, the above-noted valve-produced restriction of said area achieves control of flow rate.
To function properly at very low flow rates, the geometrical configuration of the seat and movable member of a valve must be precisely matched to close tolerances. Not only is it costly to produce high precision valves, but the narrow spacings between the seat and movable member are conducive to damage by virtue of errosive and corrosive effects and deposits caused by the fluid, and mechanical damage due to overly forceful tightening of the valve. Once damaged, most valves are not easily repairable by the simple replacement of inexpensive parts.
In many conduit systems for conveying gaseous and liquid fluids, it is desirable to utilize filtration means to remove particulate solid impurities suspended within the fluid. The installation of such filtration means into a conduit system represents additional expense.
It is accordingly an object of the present invention to provide a valve for controlling fluid flow at a low rate without need for expensive precision fabrication, and which can remove particulate solid impurities from said fluid.
It is another object of the present invention to provide a valve as in the foregoing object relatively immune to damage by forceful overtightening, and capable of repair by facile replacement of inexpensive parts.
It is a still further object of the present invention to provide a valve of the aforesaid nature of simple and rugged construction which may be economically manufactured.
These objects and other objects and advantages of the invention will be apparent from the following description.